Anatomical backgrounds on gas exchange parameters in the lung

Figure 8 Ventilation-perfusion (V_A/Q)-Diffusing capacity-perfusion (D/Q) distributions in normal and diseased lungs. A: V_A/Q and D/Q distribution in normal lung; B: That in lung with desquamative interstitial pneumonia; C: That in lung with chronic obstructive pulmonary disease characterized by emphysema. Patient with desquamative interstitial pneumonia (B) revealed minimal V_A/Q heterogeneity but very low D/Q regions that may yield “diffusion shunt” contributing to hypoxemia. Very low D/Q regions may be caused by decreased surface area and/or increased thickness of alveolocapillary membrane. Patient with chronic obstructive pulmonary disease (C) showed V_A/Q heterogeneity with high V_A/Q regions but minimal regions with very low D/Q. Modified from ref[80].